The Background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.
Referring now to FIG. 1, a HDD system 10 is shown to include a HDD printed circuit board (PCB) 14. A buffer 18 stores read, write and/or volatile control data that is associated the control of the HDD system 10. The buffer 18 usually employs volatile memory having low latency. For example, synchronous dynamic random access memory (SDRAM) or other types of low latency memory may be used. Nonvolatile memory 19 such as flash memory may also be provided to store critical data such as nonvolatile control code.
A processor 22 arranged on the HDD PCB 14 performs data and/or control processing that is related to the operation of the HDD system 10. A hard disk control module (HDC) 26 communicates with an input/output interface 24 and with a spindle/voice coil motor (VCM) driver or module 30 and/or a read/write channel module 34. The HDC 26 coordinates control of the spindle/VCM driver 30, the read/write channel module 34 and the processor 22 and data input/output with a host 35 via the interface 24.
During write operations, the read/write channel module 34 encodes the data to be written onto a read/write device 59. The read/write channel module 34 processes the write signal for reliability and may apply, for example, error correction coding (ECC), run length limited coding (RLL), and the like. During read operations, the read/write channel module 34 converts an analog read signal output of the read/write device 59 to a digital read signal. The converted signal is then detected and decoded by known techniques to recover the data that was written on the HDD.
A hard disk drive assembly (HDDA) 50 includes one or more hard drive platters 52 that include magnetic coatings that store magnetic fields. The platters 52 are rotated by a spindle motor that is schematically shown at 54. Generally the spindle motor 54 rotates the hard drive platter 52 at a controlled speed during the read/write operations. One or more read/write arms 58 move relative to the platters 52 to read and/or write data to/from the hard drive platters 52. The spindle/VCM driver 30 controls the spindle motor 54, which rotates the platter 52. The spindle/VCM driver 30 also generates control signals that position the read/write arm 58, for example using a voice coil actuator, a stepper motor or any other suitable actuator.
The read/write device 59 is located near a distal end of the read/write arm 58. The read/write device 59 includes a write element such as an inductor that generates a magnetic field. The read/write device 59 also includes a read element (such as a magneto-resistive (MR) element) that senses the magnetic field on the platter 52. The HDDA 50 includes a preamp circuit 60 that amplifies the analog read/write signals. When reading data, the preamp circuit 60 amplifies low level signals from the read element and outputs the amplified signal to the read/write channel module 34. While writing data, a write current is generated that flows through the write element of the read/write device 59. The write current is switched to produce a magnetic field having a positive or negative polarity. The positive or negative polarity is stored by the hard drive platter 52 and is used to represent data.
Referring now to FIG. 2, a digital versatile disc (DVD) system 110 is shown to include a DVD PCB 114, which includes a buffer 118 that stores read data, write data and/or volatile control code that is associated the control of the DVD system 110. The buffer 118 may employ volatile memory such as SDRAM or other types of low latency memory. Nonvolatile memory 119 such as flash memory can also be used for critical data such as data relating to DVD write formats and/or other nonvolatile control code.
A processor 122 arranged on the DVD PCB 114 performs data and/or control processing that is related to the operation of the DVD system 110. The processor 122 also performs decoding of copy protection and/or compression/decompression as needed. A DVD control module 126 communicates with an input/output interface 124 and with a spindle/feed motor (FM) driver 130 and/or a read/write channel module 134. The DVD control module 126 coordinates control of the spindle/FM driver 130, the read/write channel module 134 and the processor 122 and data input/output via the interface 124.
During write operations, the read/write channel module 134 encodes the data to be written by an optical read/write (ORW) or optical read only (OR) device 159 to the DVD platter. The read/write channel module 134 processes the signals for reliability and may apply, for example, ECC, RLL, and the like. During read operations, the read/write channel module 134 converts an analog output of the ORW or OR device 159 to a digital signal. The converted signal is then detected and decoded by known techniques to recover the data that was written on the DVD.
A DVD assembly (DVDA) 150 includes a DVD platter 152 that stores data optically. The platter 152 is rotated by a spindle motor that is schematically shown at 154. The spindle motor 154 rotates the DVD platter 152 at a controlled and/or variable speed during the read/write operations. The ORW or OR device 159 moves relative to the DVD platter 152 to read and/or write data to/from the DVD platter 152. The ORW or OR device 159 typically includes a laser and an optical sensor.
For DVD read/write and DVD read only systems, the laser is directed at tracks on the DVD that contain lands and pits during read operations. The optical sensor senses reflections caused by the lands/pits. For DVD read/write (RW) applications, a laser may also be used to heat a die layer on the DVD platter during write operations. If the die is heated to one temperature, the die is transparent and represents one binary digital value. If the die is heated to another temperature, the die is opaque and represents the other binary digital value.
The spindle/FM driver 130 controls the spindle motor 154, which controllably rotates the DVD platter 152. The spindle/FM driver 130 also generates control signals that position the feed motor 158, for example using a voice coil actuator, a stepper motor or any other suitable actuator. The feed motor 158 typically moves the ORW or OR device 159 radially relative to the DVD platter 152. A laser driver 161 generates a laser drive signal based on an output of the read/write channel module 134. The DVDA 150 includes a preamp circuit 160 that amplifies analog read signals. When reading data, the preamp circuit 160 amplifies low level signals from the ORW or OR device and outputs the amplified signal to the read/write channel module 134.
The DVD system 110 further includes a codec module 140 that encodes and/or decodes video such as any of the MPEG formats. Audio and/or video digital signal processors and/or modules 142 and 144, respectively, perform audio and/or video signal processing, respectively.